A deep-water creature once thought to be one of the world’s largest sea anemones, with tentacles reaching more than 6.5 feet long, actually belongs to a new order of animals. The finding is part of a new DNA-based study led by the American Museum of Natural History that presents the first tree of life for sea anemones, a group that includes more than 1,200 species. The report, which is published in the journal PLOS ONE, reshapes scientists’ understanding of the relationships among these poorly understood animals.